Abstract. Tobacco use remains the leading cause of preventable death in the United States, causing more than 480,000 deaths annually. Due to higher smoking prevalence, tobacco-related health problems disproportionately afflict lower income and some racial and ethnic minority groups. The presence of tobacco retailers may influence smoking behaviors through greater availability of tobacco products, lower costs of obtaining products, cheaper prices, and greater exposure to tobacco product marketing. Tobacco retailer density (TRD) is a measure of the concentration of tobacco retailers in an area, and retailer density is associated with cigarette smoking intentions, initiation, use, and cessation. The overall training objectives of this project are for the applicant to develop a theoretical understanding of how the built environment may impact health while developing multilevel and geospatial modeling and analysis skills. These skills will be used to achieve the overall project objective of examining associations of TRD with area demographics, smoking behaviors, and COPD-related hospital admission rates across the nation. While there is increasing evidence that exposure to tobacco retailers is not equitable across neighborhood demographics and that TRD may impact smoking behaviors, significant gaps in the literature remain, including: 1) a failure to consider whether neighborhood TRD depends, in part, on the demographics of surrounding area; 2) a limited number of national studies examining multilevel associations of TRD with smoking and cessation behaviors, and little attention to whether relationships may differ by neighborhood demographics; and 3) few studies that examine associations of TRD with smoking-related disease. Using secondary data, the applicant will address these gaps in the literature with three Specific Aims: 1) Using spatial econometrics, identify whether neighborhood sociodemographic compositions of census tracts surrounding a focal tract are associated with TRD; 2) Examine associations of county-level TRD with individual-level smoking and cessation behaviors; 2a) Test a moderation model to determine whether these associations vary by county-level sociodemographic compositions; and 3) Examine associations of county-level TRD with county-level COPD-related hospital admission rates. To investigate the proposed Aims, the applicant will integrate several publicly available data sources, including the 2010-2014 American Community Survey (neighborhood sociodemographics), the 2014- 2015 Tobacco Use Supplement (individual-level smoking and cessation behaviors), and the 2014 Healthcare Cost and Utilization Project State Inpatient Database (county-level COPD-related hospital admission rates). The proposed research fits within NCI?s vision, ?To eliminate smoking, and the cancers and other harms it causes, to improve public health.? My study will extend knowledge of whether TRD is associated with smoking and disease in diverse neighborhoods. The results will better equip jurisdictions to design and target tobacco control policies, such as retailer reduction or tailored cessation programs, to ameliorate area smoking risks.